Without resorting to apex you're best option is going to be switching the relationship to a master-detail. With the addition of a roll-up field you can use the count for filtering and bucketing (although this may require a formula field) in your reports.

Apex

Alternatively, if a master-detail isn't an option (usually the case if not all licenses are related to accounts), you'll want to build out a trigger to do the roll-up for you.

AppExchange

Finally, if you're okay with results not being real-time the free Rollup Helper which lets you define custom rollups with points not clicks.

Reporting

Ideally you should be able to create a report formula field and then bucket it, but that doesn't appear to be possible at this time.

Hi @Saariko If you want to get count of summary fields.My suggestion is to create a summary report and create a formula like count of All summary levels in selection.It is the best one because I had created recently a report like no of contacts on every account.